Presently, as flat-panel TV is thriving, the demand of flat-panel or thin-type speaker system in match with the flat-panel TV is increasing significantly. There are three categories of such speaker system. One category is extra-thin speaker system designed according to bending-panel-vibrating principle disclosed in NXT (U.K.) patent, the second one being thin-type speaker system manufactured by using the common cone loudspeaker, and the third one being flat-panel speaker system manufactured by using conventional flat-panel loudspeaker.
Among them, the flat-panel loudspeaker has a long history and there has been some new development thereof, such as BES patent, multi-drive technology, coaxial flat-panel loudspeaker technology etc. However, these newly developed technologies have their own problem that the upper limit of the high frequency band can not extend to cover the full audio frequency range, and the flat-panel loudspeaker has a comparably large thickness, high cost of production, difficulty in its manufacture process.
As for the NXT's patent technology, there remain two problems. The first problem is that it cannot cover full frequency range, and thus subwoofer speaker system should be needed additionally for frequency below 200 Hz. The second problem is that in the high frequency range, the sound pressure response is not flat while a flat power response can be achieved. It means that the loudspeaker has a non-flat transient frequency response and a flat long-time average response, which shall lead to bad listening.
The thin type speaker system designed with conventional loudspeakers has firstly large thickness, which may be over 6 cm in general, thus hard to match with the flat-panel TV, and secondly has a heavy weight, hard to be hang on the wall.
Clearly there exists a demand for a thin type full-range flat-panel loudspeaker, which could cover all the audio range.